In the field of containers, folding containers are widely applied because of their small size after folding, the low transportation cost of the empty containers and their usefulness when loading and unloading cargo.
As early as the mid-1970's, folding containers have been designed, researched and applied. Temporal folding containers are reconstructed from dry freight containers, and, when loaded, the folding containers are used as a complete dry freight container; when unloaded, the roof panel is removed, the two side walls are folded inward respectively, on top of which the roof is laid, and then the two end walls are folded inward. Such temporal folding containers save unloading transportation costs, but due to complicated operation, such containers were not popular until the later 1970's when the hinge for folding containers was successfully launched.
As shown in FIGS. 1 and 2, a hinge 1 for a commonly used folding container comprises an outer hinge 10 composed of two parallel plates and an inner hinge 11 provided within the outer hinge and connected with the outer hinge 10 through a pivot pin 13. A hinge top plate 12 is provided on top of the outer hinge 10, and a taper pin 14 for locking the inner hinge 11 and the outer hinge 10. A hinge top plate 12 is provided with an aperture 120 for housing the inner hinge 11, when not housing the inner hinge 11, the aperture 120 is used to place an ISO twist lock, whose width is around 60 mm, for container to containers interlocking. Taper holes 101 and 111 are provided on the outer hinge 10 and inner hinge 11, respectively, and when needed, the taper pin 14 is placed through the taper holes 101 and 111, to lock the inner hinge 11 and outer hinge 10. In order to simplify the use of the folding container, a bottom corner fitting 23 is generally welded at the bottom of the outer hinge.
As shown in FIG. 3, when hinge 1 is installed in the folding container, the outer hinge 10 is welded to bottom side rails 201 that are on two sides of base 20 of the container 2. The top of the inner hinge 11 is welded to the bottom of the corner post 210 that is on two sides of an end wall 21. When the end wall 21 is raised, the taper pin 14 locks the inner and outer hinge, so that the gap between the inner and outer hinge is quite small, which perfectly ensures the stability of the erected end wall.
The end wall functions to pile, lift and form load space together with the base and prevent cargos from longitudinal sliding. A common end wall, as shown in FIG. 4, comprises corner posts 210 placed at the two sides thereof, a top corner section 211 welded on top of the corner posts 210, a header 212 welded breadthwise on top of the two corner posts 210, a sill 213 welded breadthwise at the bottom of the two corner posts 210, and an end wall panel 214, whose four sides are welded with the corner posts 210, the header 212, and the sill 213, respectively. During the transportation of the container, the end wall suffers from transverse thrust. As shown in FIG. 4, the structure of the end wall 21 is complete and the components are connected each other by a weld. Therefore, when the top of the end wall 21 suffers from transverse thrust F, the transverse rigidity of the hinge 1 can satisfy the usage requirement. However, the structure of the end wall, as shown in FIG. 5, has only corner posts 210 located at two sides thereof (such corner posts, which bears the transverse thrust alone, are called independent corner posts). If the top of the corner post 210 suffers force F, then the transverse rigidity of the hinge 1 can hardly satisfy the usage requirement. Because the width of the aperture 120 on the hinge top plate 12 is around 63 mm, it is almost impossible to enhance the inner hinge along the width direction to satisfy the usage requirement.